Under the current standards established by the United States Department of Agriculture (USDA), beef from bulls, steers, and heifers is classified into eight different quality grades. Beginning with the highest and continuing to the lowest, the eight quality grades are prime, choice, select, standard, commercial, utility, cutter and canner. The characteristics which are used to classify beef include color, texture, firmness, and marbling, a term which is used to describe the relative amount of intramuscular fat of the beef. Well-marbled beef from steers and heifers, i.e., beef that contains substantial amounts of intramuscular fat relative to muscle, tends to be classified as prime or choice; whereas, beef that is not marbled tends to be classified as select. Beef that is classified as prime or choice, typically, is sold at higher prices than beef that is classified into lower quality grades.
Classification of beef into different quality grades is a subjective process which occurs at the packing facility and involves visual inspection of a region between the 12th and 13th rib of a beef carcass by a certified USDA grader. The grader relies on pictures and other objective aids to make his determinations as to color, texture, firmness, and marbling. Unfortunately, the visual appraisal by the grader is costly, labor intensive, and time-consuming. Moreover, the visual appraisal of a beef carcass cannot occur until the animals are harvested.
Currently there are no methods for identifying live cattle that have or that lack the genetic potential to produce beef that is well-marbled. Such information could be used by the cattle producer to channel calves into particular feeding regimens and to meet the requirements of specific marketing programs. Such information could also be used to identify cattle that are good candidates for breeding. Thus, it is desirable to have a method which can be used to assess the beef marbling potential of live cattle, particularly young cattle.
Another characteristic of beef that is desired by consumers is tenderness. Currently there are no procedures for identifying live animals whose beef, if cooked properly, would be tender Currently, there are two procedures which are used by researchers to assess the tenderness of beef after it has been cooked. The first involves a subjective analysis by a panel of trained testers. The second is the Warner-Bratzler shear force procedure which involves an instrumental measurement of the force required to shear steaks, chops, and ground patties of cooked beef. Both methods are costly and time-consuming and, thus, are not practical on a large scale. Consequently, neither procedure is used at a packing facility. Accordingly, it is desirable to have new methods which can be used to identify carcasses and live cattle that have the potential to provide beef that, if cooked properly, will be tender.